There are 2 in the area ... 1 north on Rt 2 and one south on Rt 2.
North on Rt2 will take you into Grand Isle. Right behind the A&B Market in Grand Isle is Bill's Sport Shop. Call to make sure he has bait that time of year ... some only carry it for the winter.
South on Rt 2 heading back toward I-89 (you'll pass it on your way to South Hero), there is Dockside Bait and Tackle. I believe they have bait yearround, and they also have a nice selection of lures, etc in there.
Good luck!